OBD Code P0122 – What Does This Mean? How Can It Be Fixed?

OBD code P0122 is a generic diagnostic trouble code for throttle position sensor circuit malfunction. The throttle position sensor (TPS) tells your engine computer how far you have opened the throttle.

This is important because it helps the Engine Control Module (ECM) determine how much fuel to inject into the combustion chamber – whether to send more air through the Exhaust Gas Recirculation Valve (EGR valve) and when to open up the secondary air injection valves. If this sensor malfunctions, it will cause your vehicle’s engine performance to suffer.

OBD Code p0122

P0122 – OBD-II Trouble Code

What is OBD-II?

OBD-II stands for On-Board Diagnostics, a standard established by the U.S. Environmental Protection Agency (EPA) in 1996. The OBD system regulates emissions from your vehicle by monitoring its performance and checking for faulty sensors or computer systems. The information collected by the OBD system is relayed to your dashboard via diagnostic trouble codes (DTC).

DTCs are numerical codes used to identify a problem with your car within its engine management systems or electronic control units (ECUs).

Throttle Position (TP) Sensor Circuit Low Voltage

The throttle position sensor (TPS) is used to inform the engine control unit of the throttle valve’s position. It does this by monitoring the voltage output received from the sensor. This sensor produces an output voltage that is directly proportional to the throttle plates, meaning that when the accelerator pedal is pushed, the TPS will send a higher voltage to the ECM.

When the engine is idle, the TPS will send a low-voltage reading to the ECU. If a fault code has been stored and it is severe enough to cause the ECM to fail, you won’t be able to start or run your car or truck.

If ECM is not getting a signal from the TPS, this could be because the TPS is not working, or it does not have the proper voltage. It could also be because the wiring to the TPS is damaged and open in some places, which would cause an open circuit between the ECM and TPS.

The TPS may also be loose or contaminated with oil or other substances that would prevent good electrical connections when plugged into its harnesses.

What Causes a P0122 Code?

1. Faulty TPS

P0122 is a code that indicates that the TPS (Throttle Position Sensor) is faulty. The TPS can’t accurately tell when to open and close the throttle blades because it’s getting inaccurate information from its sensors. This causes the engine to run poorly, which results in a decrease in fuel economy and an increase in carbon monoxide emissions.

2. Faulty Wiring

Wiring can be damaged by improper handling and installation. Water from rain can also get into your OBD port through gaps in the vehicle’s bodywork and cause corrosion on electronic components such as connectors and terminals inside the port. This can lead to the corrosion of connectors themselves if it is not cleaned correctly after being exposed to water for an extended period of time.

3. Faulty Engine Controle Module (ECM)

The engine control module (ECM) is a computer that controls your vehicle’s engine. It’s connected to various sensors that monitor the vehicle’s systems and make adjustments as needed.

The ECM also monitors the throttle position sensor, which tells it whether or not to adjust the throttle plate that controls fuel injection into your engine. When there’s an issue with the ECM, it can cause one of two problems: OBD II codes or no codes at all.

If you get an error code upon scanning OBD II, it means there’s something wrong with your ECM. If you get no error code at all (and still receive poor performance), then this means that either something else besides the ECM is broken or there is something wrong with how data from other systems reaches your car’s computer.

For any repairs to be made successfully in either scenario above, we highly recommend seeking professional help from a mechanic who knows what they’re doing when it comes down to diagnosing and repairing an OBD II system like yours.

4. Faulty Sensors

Sensors can be contaminated with deposits, such as oil or moisture, that prevent them from performing their functions as intended and cause the error code to appear on the dashboard display.

A dirty sensor is also known as a fouled sensor because of its build-up of contaminants, which results in poor electrical conductivity and reduced functionality of the component. The following are some common causes for this issue:

  • Sensor washer system malfunctioning or not functioning properly, for example, clogged nozzles.
  • Inadequate lubrication during service intervals that require an inspection/lube procedure, for example, manual transmission fluid change.

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Common Symptoms of P0122 Code

1. Engine Misfire

Your car’s OBD-II system is designed to detect any problems in your vehicle. The check engine light will come on, signaling an issue with your car. This can be due to a variety of things, including faulty sensors or a stuck open fuel cap.

However, one of the most common reasons for this type of warning is engine misfire.

2. Engine Light

The engine light is a warning light. A visual indicator that something is wrong with your vehicle. It will come on when the engine is running and the check engine (ECM) system detects an emissions-related concern.

When this code is set, it means that your vehicle has detected an issue with one of its sensors.

In most cases, these sensors are used to monitor incoming airflow into the engine or coolant temperature levels in order to determine if any harm has been done to critical components within your car’s drivetrain. These drivetrains include catalytic converters or oxygen sensors which help prevent excess carbon monoxide from entering your exhaust pipes.

Related Post: OBD Code P1259

3. High Idle

The high idle speed could be caused by a faulty idle air control valve. The idle air control valve regulates the amount of air flowing into the throttle body. The PCM controls airflow through this valve based on engine load, engine temperature, and other conditions.

If you have determined that your car’s high idle speed is due to a faulty IACV, it should be replaced with a new one from an auto parts store or dealership as soon as possible preferably before driving long distances or leaving town for an extended period of time.

4. Stalling or Surging

If you’re experiencing stalling or surging, your vehicle may be experiencing a problem with its Throttle Position (TP) sensor. The TP sensor is responsible for sending signals to the ECM, which then tells your engine’s computer how much power it needs to apply.

If the TP sensor is faulty, it could result in an incorrect reading and cause an over-fueling issue resulting in stalling or surging at idle speeds and when accelerating from a stop.

The TP sensor can be tested using a digital multimeter that measures the resistance between connections on components such as connectors, wires, and circuits.

If this test shows no issues with the TP sensor itself, then you’ll want to look elsewhere for a solution such as replacing it altogether or cleaning it thoroughly before recalibrating it back into working order again.

5. Hesitation Upon Acceleration

If you’re experiencing hesitation upon acceleration, this could be a sign that there is an issue with your throttle body. There are several other things to check to ensure the throttle body isn’t causing your car’s hesitation when accelerating.

Another component that may cause hesitation is the throttle position sensor (TPS). The TPS can become dirty or damaged over time and cause erratic readings from the engine control computer (ECC), which will result in a misfire situation if it continues for too long.

Symptoms Caused by Other Problems in Addition to P0122 Code

In rare cases, the code may be triggered by a problem unrelated to the oxygen sensors. In these cases, there are other symptoms that can occur along with P0122. These include, but are not limited to:

  • The engine may not start or it may die while driving.
  • The engine may run roughly (the engine will vibrate more than usual).
  • Acceleration may be slower when you step on the gas pedal to go faster. This can cause your vehicle to feel sluggish or slow when accelerating from a stop sign or traffic light.
  • The idle speed (engine RPM) will fluctuate higher than usual during idling when cold and return to normal after reaching operating temperature.
  • You experience difficulty shifting gears while driving at high speeds because of problems shifting into gears at low rpm (low revolutions per minute).

Related Post: OBD Code P2196

How to Fix Code P0122

1. Reconnect the Throttle Position Sensor

The first step to fixing code P0122 is to reconnect the wiring harness that connects your engine control module (ECM) to the vehicle’s sensors. If this does not work, try disconnecting and reconnecting each of these connections:

  • The wiring harness connects the ECM to other components like a camshaft position sensor (CPS) or fuel injection pump pressure regulator valve (PVRV).
  • The wiring harness connects an air/fuel ratio sensor (O2S), coolant temperature sensor, manifold absolute pressure sensor, manifold vacuum switch, or oxygen sensor.
  • Any wires connected directly to an EGR valve solenoid valve body assembly or oxygen sensor heater unit assembly.

2. Visit a Professional Mechanic

There is nothing like giving your car to a professional to fix. Whatever the issue is. If your car has a code P0122 problem, then it’s advisable to get it checked by a mechanic even if you think you can sort it out yourself.


If your car has a P0122 code, it means that the throttle position sensor (TPS) is not working correctly. The TPS sends information about how much gas is being applied by the driver to the engine control module (ECM). Without this information, the ECM can’t control idle speed or fuel mixture for optimum performance and emissions control.

Once your car has a faulty TPS, you might start experiencing, rough acceleration, stalling, check engine light, engine misfire, etc. To fix this, ensure that your TPS is fixed then make sure to check the ECM. Your car should be as good as new afterward.